Quality control and the differential leukocyte count.
The differential leukocyte count (DLC) has been an important semi-quantitative method for describing the leukocyte population as visualized on examination of the peripheral blood film. Evaluation of the DLC was never a diagnostic procedure in its own right, nor was it the primary purpose of the blood film evaluation. It is the most time-consuming element of the blood film examination, and therefore a primary candidate for automation, which in turn has led to an artificial separation of DLC enumeration from blood film evaluation. Nevertheless, it is being used as a quality assurance test for automated DLC procedures. While this may divert valuable effort away from the central function of the diagnostic haematology laboratory, namely haematological diagnosis, it has become a quality assurance requirement. Quality is best assured when haematological case data, including history, cell counts, indices, and DLC data, are evaluated by appropriately trained experts before being reported to clinicians, with examination of the blood film as indicated.
Bentley
S A
SA
Department of Pathology, University of North Carolina School of Medicine, Chapel Hill 27514.
D001331:Automation / Q000295:instrumentation / Q000592:standards; D006801:Humans; D007958:Leukocyte Count / Q000295:instrumentation*; D015588:Observer Variation; D011786:Quality Control; D015203:Reproducibility of Results